scholarly journals The Influence of Competition Trait-Mediated Effects on Intra-Guild Predation System

2021 ◽  
Author(s):  
Zhang Rong ◽  
Zhou Shuai ◽  
Zhu Wenjun ◽  
Zhou Xiaomei
Keyword(s):  
Population Dynamics ◽  
Interspecific Competition ◽  
Intraspecific Competition ◽  
Mutual Influence ◽  
Equation Model ◽  
Chemical Effect ◽  
Enhancement Effect ◽  
Susceptible Population ◽  
Infected Population ◽  
Mediated Effects

Abstract Parasitism can affect the population dynamics in many ways, and its indirect effect is easy to be ignored, that is, it can weaken the host's behavior, physiology and psychology to affect the whole population. In this paper, we build a differential equation model by adding four parameters to study the influence of multiple competitive relationships on the predator-prey system, It includes the enhancement effect g of intraspecific competition and the enhancement effect h of interspecific competition between susceptible population and infected population, the weakening effect m of intraspecific competition and the weakening effect n of interspecific competition between susceptible population and infected population. Through the analysis, it can be concluded that a single g or m can promote the symbiosis of predator and prey, a single h has little effect on the population dynamics, and a single n is not conducive to the symbiosis; The fusion of g and h promotes coexistence, but the fusion of m and n is on the contrary; Interestingly, the combination of multiple regulatory parameters has a chemical effect on the survival of species, but the combination of g, m and h can inhibit coexistence, while the combination of g, m and n can promote coexistence. The reason is that the combination of parameters is not a simple addition of effects, but a prerequisite for mutual influence. To sum up, the research content provides a reference for considering the role of multiple factors, and provides theoretical guidance for explaining ecological phenomena and proving ecological conclusions.

Competition betweenElymus elymoidesandTaeniatherum caput-medusae

Weed Science ◽  
1999 ◽  
Vol 47 (6) ◽  
pp. 720-728 ◽  
Author(s):  
David W. Clausnitzer ◽  
Michael M. Borman ◽  
Douglas E. Johnson
Keyword(s):  
Soil Moisture ◽  
Interspecific Competition ◽  
Seed Production ◽  
Intraspecific Competition ◽  
Field Experiments ◽  
Block Design ◽  
Low Oxygen ◽  
Competitive Effects ◽  
Growing Seasons ◽  
Randomized Block Design

Two field experiments were conducted from 1993–1994 through 1995–1996 growing seasons in Harney County, OR, to determine the relative competitive abilities ofElymus elymoides(squirreltail) a native perennial range grass, andTaeniatherum caput-medusae(medusahead), an exotic annual grass weed. The 1993–1994 growing season was very dry, 1994–1995 was dry, and 1995–1996 was wetter than average. One experiment tested seedlings vs. seedlings in each of three seasons. The second experiment tested seedlings plus second- and third-year establishedE. elymoidesplants vs. 77caput-medusaeover 2 yr. Biomass, seed production, and soil moisture utilization 15, 30, 45, and 60 cm deep by the two species were measured. A randomized block design with factorial arrangement was used, with 25 2.25-m2plots per block. Initial seeding densities of each species were 0, 10, 74, 550, and 4,074 seeds m−2in all combinations of density. In the seedling vs. seedling experiment, intraspecific competition by 77caput-medusaeon itself was always significant (P ≤ 0.10) for both biomass and seed production. Interspecific competition byE. elymoidesseedlings onT. caput-medusaebiomass and seed production was not significant (P ≥ 0.10) in 2 of 3 yr and was always less than intraspecific competition by 77caput-medusae. Only 0.4% ofE. elymoidesseed germinated, and no seed was produced in the very dry first year, but 84% of remaining seed was viable for the next year, which had better moisture conditions for germination and establishment. Interspecific competition affected (P ≤ 0.10)E. elymoidesseedling biomass and seed production throughout the study. Intraspecific competition affected (P ≤ 0.10) seedlingE. elymoidesseed production in the dry year but not in the wetter than average year. In the matureE. elymoidesexperiment, intraspecific competition byT. caput-medusaeon weight and seed production per plant was greater than interspecific competition fromE. elymoides. Seedling/matureE. elymoidesreducedT. caput-medusaeweight per plant in the dry year but the effect was not biologically significant. Larger, matureEelymoidesplants produced 600 to 3,000 seeds per plant during the wet year; neither intra- nor interspecific competition was a factor.Taeniatherum caput-medusaewas better able to access deeper soil moisture and was more aggressive at extracting soil moisture than wereE. elymoidesseedlings in the wet year. Cold soils and low oxygen due to wet soils may have restrictedE. elymoidesseedling root activity. MatureE. elymoidesplants did not appear restricted by cold soils or low oxygen. Established second- and third-yearE. elymoidesplants were able to compete for soil moisture down to 45 cm. The generally greater interspecific competitive effects ofT. caput-medusaeonE. elymoidesthan vice versa suggested that it will be difficult to establish anE. elymoidesstand in an existingT. caput-medusaecommunity without first suppressingT. caput-medusae. IndividualE. elymoidesplants did establish and were productive with and withoutT. caput-medusaecompetition.

The population dynamics of Cardiaspina albitextura (Psyllidae).

1964 ◽  
Vol 12 (3) ◽  
pp. 362 ◽  
Author(s):  
LR Clark
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Population Study ◽  
Intraspecific Competition ◽  
Limited Availability ◽  
Host Trees ◽  
Increase With Increase ◽  
Numerical Stabilization ◽  
Environmental Agencies ◽  
Population Numbers

During the last 16 years, the numbers of Cavdiaspina albitextura rose from low to high in many places, and either remained high or eventually resumed their original levels. In other places, the numbers of the psyllid remained low although they fluctuated considerably. The results of a population study which began in 1952 suggest that, in parts of the woodland colonized by C. albitextura, the stabilization of psyllid numbers occurred temporarily - in some areas at low mean levels of population density and in others at high mean levels. In other parts of the woodland, psyllid numbers changed progressively with time. The occurrence of numerical stabilization appeared to depend upon the extent of the mortality caused directly or indirectly by certain environmental agencies whose "deciding" or "conditioning" influence determined when and where stabilization was possible. At low psyllid densities, the principal conditioning agencies were probably the whole complex of species predacious on psyllid nymphs and eggs, and weather. At high psyllid densities, the conditioning agencies were the density of host trees, and wind. Providing that sufficient mortality was caused by the conditioning agencies, negative feed-back mechanisms were able to implement stabilization. At low psyllid densities, birds predacious on adult psyllids appeared to be the operative or "density-governing" agency. The intensity of their attacks, which tended to increase with increase in psyllid density, operated in a probabilistic manner to limit increase in population numbers. At high psyllid densities, food and space favourable for oviposition were the operative agencies. The limited availability of food and space brought into action a stabilizing mechanism which functioned automatically through forms of intraspecific competition.

Plant Water Stress of Soybean (Glycine max) and Common Cocklebur (Xanthium pensylvanicum): A Comparison Under field Conditions

Weed Science ◽  
1979 ◽  
Vol 27 (3) ◽  
pp. 285-289 ◽  
Author(s):  
H. D. Scott ◽  
R. D. Geddes
Keyword(s):  
Glycine Max ◽  
Water Stress ◽  
Interspecific Competition ◽  
Intraspecific Competition ◽  
Vegetative Growth ◽  
Species Differences ◽  
Plant Water ◽  
Plant Water Stress ◽  
Diffusive Resistance ◽  
Early Afternoon

The study was conducted to determine the seasonal and diurnal water stress of soybeans [Glycine max (L.) Merr. ‘Lee 74′] grown under intraspecific competition (competition between plants of the same species) and interspecific competition (competition between plants of different species) with common cocklebur (Xanthium pensylvanicum Wallr.). Midday xylem potentials decreased as the season progressed and were lower in common cocklebur during vegetative growth of soybean and in soybean during reproductive growth. For a given species differences in xylem potential due to mode of competition were small. In the diurnal studies xylem potential for each species decreased to a minimum in the early afternoon but recovered to the original pre-dawn values at night. As the season progressed leaf xylem potential (a) decreased at a greater rate, (b) decreased sooner in the day, and (c) recovered at a slower rate. It was shown that differences in xylem potential between soybean and common cocklebur on a given day were small. Greater diffusive resistance values generally were found with soybean than with common cocklebur and with each species grown under interspecific competition.

Growth Rate and Long-Term Population Dynamics of Jarrah (Eucalyptus marginata Donn ex Sm.) Regeneration in Western Australian Forest

1984 ◽  
Vol 32 (4) ◽  
pp. 353 ◽  
Author(s):  
I Abbott ◽  
O Loneragan
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Intraspecific Competition ◽  
Substantial Reduction ◽  
Eucalyptus Marginata ◽  
Low Intensity ◽  
Rates Of Growth ◽  
Western Australian ◽  
Survival Of Seedlings

Five of the six stages in the regeneration of jarrah (seedling, lignotuberous seedling, seedling coppice, ground coppice and sapling) were studied in detail. Survival of seedlings is variable but usually low, and growth into the ground coppice stage usually takes 15-20 years. Growth into the sapling stage is arrested until there is substantial reduction in intraspecific competition. Lignotuberous seedlings, seedling coppice and ground coppice growing in ashbeds show faster rates of growth in length of the long axis of the lignotuber and length of the tallest shoot. Logging and prescribed (low-intensity) fires are associated with development of more seedling coppice and growth of ground coppice into saplings and poles than is fire alone.

Competition between endoparasitic nematodes and effect on biomass of Ammophila arenaria (marram grass) as affected by timing of inoculation and plant age

Nematology ◽  
2005 ◽  
Vol 7 (2) ◽  
pp. 169-178 ◽  
Author(s):  
Wim van der Putten ◽  
Henk Duyts ◽  
E. Pernilla Brinkman
Keyword(s):  
Interspecific Competition ◽  
Intraspecific Competition ◽  
Plant Biomass ◽  
Nematode Species ◽  
Pratylenchus Penetrans ◽  
Agricultural Systems ◽  
Ammophila Arenaria ◽  
Marram Grass ◽  
Natural Dune ◽  
Dune Grass

AbstractWe studied the effects of intra- and interspecific competition on the abundance of endoparasitic nematodes and assessed the consequences for biomass production of the natural dune grass Ammophila arenaria. Pratylenchus penetrans was limited by intraspecific competition and it suppressed the abundance of Heterodera arenaria, whilst the interaction between H. arenaria and Meloidogyne maritima was neutral. Pratylenchus penetrans and H. arenaria reduced plant biomass, whereas M. maritima did not. Plant biomass was not differently affected by adding one or two nematode species. When added to older plants, numbers of H. arenaria and M. maritima were higher but numbers of P. penetrans were lower, resulting in less reduction of plant biomass. We discuss our results on this natural system with respect to patterns of interspecific nematode competition observed in agricultural systems.

A three variable differential equation model for gypsy moth population dynamics

1994 ◽  
Vol 72 (3-4) ◽  
pp. 229-250 ◽  
Author(s):  
J.W. Wilder ◽  
N. Voorhis ◽  
J.J. Colbert ◽  
A. Sharov
Keyword(s):  
Differential Equation ◽  
Population Dynamics ◽  
Gypsy Moth ◽  
Equation Model ◽  
Differential Equation Model ◽  
Moth Population

Population dynamics in echinococcosis and cysticercosis: mathematical model of the life-cycles of Taenia hydatigena and T. ovis

Parasitology ◽  
1987 ◽  
Vol 94 (1) ◽  
pp. 181-197 ◽  
Author(s):  
M. G. Roberts ◽  
J. R. Lawson ◽  
M. A. Gemmell
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
New Zealand ◽  
Equation Model ◽  
Life Cycles ◽  
Control Measures ◽  
Taenia Hydatigena ◽  
Infection Pressure ◽  
Lower Infection ◽  
Compare And Contrast

SUMMARYIt is shown that under the conditions that prevailed in New Zealand in the late 1950s, Taenia hydatigena was hyperendemic, the life-cycle being regulated by a density-dependent constraint in the form of acquired immunity, and T. ovis was rare. The control measures that caused Echinococcus granulosus, which was endemic at the time, to decline towards extinction reduced T. hydatigena and T. ovis to endemic status only. A non-linear integrodifferential equation model, which was previously linearized to describe the life-cycle of E. granulosus in dogs and sheep in New Zealand, is used to describe the life-cycles of T. hydatigena and T. ovis. The model is then used to compare and contrast the population dynamics of these three species. The model is used to demonstrate that the endemic steady state is structurally unstable, and may be asymptotically unstable to small perturbations. It is also shown that despite the lower infection pressure experienced by the intermediate host in the endemic state, the numbers of larvae in sheep may be higher than in the hyperendemic state. Finally it is shown that the partial success of the control measures against T. hydatigena may have caused an increase in the numbers and prevalence of T. ovis larvae in sheep due to the reciprocal immunity between the two species.

scholarly journals Recession of Tussilago farfara (L.) population from the agro coenose as a result of cultivation abandonment. I The effect of fallowing on population dynamics

2014 ◽  
Vol 57 (3) ◽  
pp. 371-386
Author(s):  
Anna Namura-Ochalska
Keyword(s):  
Population Dynamics ◽  
Spatial Structure ◽  
Interspecific Competition ◽  
Population Size ◽  
Dactylis Glomerata ◽  
Tussilago Farfara ◽  
Agropyron Repens

The paper evaluates the effect of fallowing on seasonal and multiyear dynamics, as well as on the spatial structure of <em>Tussilago farfara</em> population. In four years turfing and rapid increase in the size of grass populations - those of <em>Agropyron repens</em> (L.) PB. and <em>Dactylis glomerata</em> caused the elimination of <em>Tussilago farfara</em> population. The studies have showed that a decrease in the population size resulted from hampering of both vegetative and generative reproduction. The interspecific competition for available space seems to be a crucial factor limiting emergence of new shoots. In the agrocoenose big population size of <em>Tussilago farfara</em> remained throughout the studies.

scholarly journals Social Psychology of Coronavirus Disease 2019: Do Fatalism and Comparative Optimism Affect Attitudes and Adherence to Sanitary Protocols?

2021 ◽  
Vol 12 ◽  
Author(s):  
Trond Nordfjaern ◽  
Milad Mehdizadeh ◽  
Mohsen Fallah Zavareh
Keyword(s):  
Structural Equation ◽  
Spreading Rate ◽  
Equation Model ◽  
Direct And Indirect Effects ◽  
Social Psychological ◽  
Comparative Optimism ◽  
Multidimensional Measure ◽  
Health Measures ◽  
Mediated Effects

The potential of mitigating the spreading rate and consequences of the coronavirus disease 2019 (COVID-19) currently depends on adherence to sanitary protocols (e.g., hand hygiene and social distancing). The current study aimed to investigate the role of fatalism and comparative optimism for adherence to COVID-19 protocols. We also tested whether these factors are directly associated with adherence or associated through attitudinal mediation. The results were based on a web survey conducted among university students (n = 370) in Tehran, Iran. The respondents completed a multidimensional measure of fatalism (general fatalism, internality, and luck) and measures of comparative optimism, attitudes toward COVID-19 health measures, and adherence. The estimated structural equation model explained approximately 40% of the total variance in attitudes toward COVID-19 protocols and adherence. As expected, high internality was associated with stronger adherence, whereas luck was associated with weaker adherence. Comparative optimism was more strongly associated with adherence than fatalism, and somewhat unexpectedly comparative optimism was associated with stronger adherence. Analyses of direct and indirect effects suggested that fatalism was mainly mediated through attitudes, whereas comparative optimism had both direct and mediated effects. The findings are discussed in relation to the role of these social psychological factors for COVID-19 mitigation.

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